feat: add stats/incr/nanmmae

[anxhukumar]

Resolves #5582

Description

What is the purpose of this pull request?

This pull request:

• Adds the @stdlib/stats/incr/nanmmae package, which computes an incremental mean absolute error while ignoring NaN values.

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves [RFC]: add stats/incr/nanmmae #5582

Questions

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No

Other

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Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nanmmae	$\color{green}146/146$ $\color{green}+100.00\%$	$\color{green}8/8$ $\color{green}+100.00\%$	$\color{green}2/2$ $\color{green}+100.00\%$	$\color{green}146/146$ $\color{green}+100.00\%$

The above coverage report was generated for the changes in this PR.